Centennial Assessment of Greenhouse Gases Emissions of Young and Old Hydroelectric Reservoir in Mediterranean Mainland

Abstract

The quantities of emitted greenhouse gases (GHG) from hydroelectric reservoirs around the world, especially in warm latitudes, have tarnished the green credentials of hydroelectric energy. The accurate measurement and evaluation of the emitted GHG, which is a critical element in climate change policy, present a significant challenge. Many works have been focused on GHG emissions assessment from reservoirs around the world, but there are no available data concerning reservoirs in Mediterranean countries. In this study, emitted GHG from a young and an old in line water reservoirs, located in Mediterranean mainland, were collected using a “static floating chamber”. Methane and carbon dioxide concentrations were measured and their specific emission rates were calculated. The data were used for the development of a mathematical prediction model, proposed for GHG emission assessment. Statistical correlation of GHG emissions and water physicochemical characteristics led to the interpretation of the biochemical processes taking place into the reservoirs. Furthermore, the impact of reservoir’s morphology on GHG emissions was recorded, enhancing its importance on decision making for "green" energy investments. The results of this study indicate that artificial reservoirs in Mediterranean mainland generally have lower GHG emissions than those located in tropical and subtropical climatic zones and higher than those in continental subarctic zones and approach the highest values of CO2 emissions and the mean CH4 emissions recorded in continental climatic zones. The applied methodology provides a comprehensive tool for the long term (centennial) emissions assessment and the assessment of reservoirs impacts on the environment.

Keywords: carbon dioxide fluxes, climate change, floating chamber, hydroelectric dam, methane fluxes, reservoir morphology, water reservoir